diff --git a/.github/checks-manifest.yaml b/.github/checks-manifest.yaml
index 166c8a4f45e..0217937a23f 100644
--- a/.github/checks-manifest.yaml
+++ b/.github/checks-manifest.yaml
@@ -49,6 +49,11 @@ checks:
     triggers: [".github/workflows/desktop_qualify_beta.yml", ".github/scripts/check-release-process-guards.py", "scripts/run-release-process-guards.sh", "backend/tests/unit/test_desktop_release_scripts.py", ".github/checks-manifest.yaml"]
     lanes: ["local", "ci"]
     reason: "SCA-174: qualification must check out the exact release tag inside its isolated source directory; the guard and its focused behavioral test run on every relevant diff"
+  - id: windows-release-sync-pr-lifecycle
+    command: ["python3", ".github/scripts/test_retire_superseded_windows_sync_prs.py"]
+    triggers: [".github/workflows/desktop_windows_release.yml", ".github/scripts/retire_superseded_windows_sync_prs.py", ".github/scripts/test_retire_superseded_windows_sync_prs.py", ".github/checks-manifest.yaml"]
+    lanes: ["local", "ci"]
+    reason: "#10727: a replacement Windows version-sync PR must retire only older same-repository sync PRs; nine superseded PRs accumulated when one-shot auto-merge could not pass branch protection"
   - id: failure-class-retirement-author
     command: ["python3", ".github/scripts/test_failure_class_retirement.py"]
     triggers: [".github/scripts/failure_class_retirement.py", ".github/scripts/test_failure_class_retirement.py", ".github/workflows/repo-hygiene.yml", "scripts/failure-class", ".github/checks-manifest.yaml"]
diff --git a/.github/failure-classes/FC-superseded-windows-sync-pr-lifecycle.json b/.github/failure-classes/FC-superseded-windows-sync-pr-lifecycle.json
new file mode 100644
index 00000000000..e3a08a50a37
--- /dev/null
+++ b/.github/failure-classes/FC-superseded-windows-sync-pr-lifecycle.json
@@ -0,0 +1,18 @@
+{
+  "schema_version": 1,
+  "id": "FC-superseded-windows-sync-pr-lifecycle",
+  "violated_contract": "Only the newest unmerged Windows release version-sync PR remains actionable; once a replacement PR exists, older same-repository sync PRs must stop competing for review.",
+  "canonical_prevention": "The Windows release workflow confirms its current same-repository main-targeting sync PR, then retires only strictly older exact-semver release/windows-v* PRs without deleting release state or blocking publication.",
+  "canonical_prevention_artifact": [
+    ".github/scripts/retire_superseded_windows_sync_prs.py",
+    ".github/scripts/test_retire_superseded_windows_sync_prs.py"
+  ],
+  "evidence_prs": [
+    10729
+  ],
+  "scope_hints": [
+    ".github/workflows/desktop_windows_release.yml",
+    ".github/scripts/retire_superseded_windows_sync_prs.py"
+  ],
+  "status": "open"
+}
diff --git a/.github/scripts/retire_superseded_windows_sync_prs.py b/.github/scripts/retire_superseded_windows_sync_prs.py
new file mode 100644
index 00000000000..869ab0dc0be
--- /dev/null
+++ b/.github/scripts/retire_superseded_windows_sync_prs.py
@@ -0,0 +1,199 @@
+#!/usr/bin/env python3
+"""Close Windows version-sync PRs superseded by a newer release."""
+
+from __future__ import annotations
+
+import argparse
+import json
+import os
+import re
+import subprocess
+import sys
+from collections.abc import Callable, Sequence
+from dataclasses import dataclass
+from typing import TextIO
+
+WINDOWS_SYNC_BRANCH_RE = re.compile(r"^release/windows-v(\d+)\.(\d+)\.(\d+)$")
+Version = tuple[int, int, int]
+Runner = Callable[..., subprocess.CompletedProcess[str]]
+
+
+@dataclass(frozen=True)
+class SyncPullRequest:
+    number: int
+    branch: str
+    version: Version
+
+
+def parse_version(value: str) -> Version:
+    match = re.fullmatch(r"(\d+)\.(\d+)\.(\d+)", value)
+    if match is None:
+        raise argparse.ArgumentTypeError("version must use MAJOR.MINOR.PATCH")
+    return tuple(int(part) for part in match.groups())
+
+
+def format_version(version: Version) -> str:
+    return ".".join(str(part) for part in version)
+
+
+def decode_sync_pr(raw: object) -> SyncPullRequest | None:
+    if not isinstance(raw, dict):
+        return None
+    number = raw.get("number")
+    branch = raw.get("headRefName")
+    if (
+        not isinstance(number, int)
+        or isinstance(number, bool)
+        or not isinstance(branch, str)
+        or raw.get("baseRefName") != "main"
+        or raw.get("isCrossRepository") is not False
+    ):
+        return None
+    match = WINDOWS_SYNC_BRANCH_RE.fullmatch(branch)
+    if match is None:
+        return None
+    return SyncPullRequest(
+        number=number,
+        branch=branch,
+        version=tuple(int(part) for part in match.groups()),
+    )
+
+
+def select_superseded_prs(
+    raw_prs: object,
+    *,
+    current_pr: int,
+    current_version: Version,
+) -> list[SyncPullRequest] | None:
+    if not isinstance(raw_prs, list):
+        return None
+
+    sync_prs = [decoded for raw in raw_prs if (decoded := decode_sync_pr(raw)) is not None]
+    current = next((pr for pr in sync_prs if pr.number == current_pr), None)
+    if current is None or current.version != current_version:
+        return None
+
+    return sorted(
+        (pr for pr in sync_prs if pr.number != current_pr and pr.version < current_version),
+        key=lambda pr: (pr.version, pr.number),
+    )
+
+
+def retire_superseded_prs(
+    *,
+    repository: str,
+    current_pr: int,
+    current_version: Version,
+    runner: Runner = subprocess.run,
+    stdout: TextIO = sys.stdout,
+    stderr: TextIO = sys.stderr,
+) -> int:
+    listing = runner(
+        [
+            "gh",
+            "pr",
+            "list",
+            "--repo",
+            repository,
+            "--base",
+            "main",
+            "--state",
+            "open",
+            "--limit",
+            "200",
+            "--json",
+            "number,headRefName,baseRefName,isCrossRepository",
+        ],
+        check=False,
+        capture_output=True,
+        text=True,
+    )
+    if listing.returncode != 0:
+        print("Warning: could not list Windows sync PRs; cleanup skipped.", file=stderr)
+        return 0
+
+    try:
+        raw_prs = json.loads(listing.stdout)
+    except json.JSONDecodeError:
+        print("Warning: gh returned invalid Windows sync PR JSON; cleanup skipped.", file=stderr)
+        return 0
+
+    superseded = select_superseded_prs(
+        raw_prs,
+        current_pr=current_pr,
+        current_version=current_version,
+    )
+    if superseded is None:
+        print(
+            f"Warning: current Windows sync PR #{current_pr} was not confirmed; cleanup skipped.",
+            file=stderr,
+        )
+        return 0
+
+    current_version_text = format_version(current_version)
+    closed = 0
+    for pull_request in superseded:
+        comment = (
+            f"Superseded by Windows release sync PR #{current_pr} "
+            f"(v{current_version_text}). The release tag remains authoritative; "
+            "no tag, release, or branch was deleted."
+        )
+        result = runner(
+            [
+                "gh",
+                "pr",
+                "close",
+                str(pull_request.number),
+                "--repo",
+                repository,
+                "--comment",
+                comment,
+            ],
+            check=False,
+            capture_output=True,
+            text=True,
+        )
+        if result.returncode != 0:
+            print(
+                f"Warning: could not close superseded Windows sync PR #{pull_request.number}.",
+                file=stderr,
+            )
+            continue
+        closed += 1
+        message = (
+            f"Closed superseded Windows sync PR #{pull_request.number} " f"(v{format_version(pull_request.version)})."
+        )
+        print(
+            message,
+            file=stdout,
+        )
+
+    print(f"Retired {closed} superseded Windows sync PR(s).", file=stdout)
+    return closed
+
+
+def main(argv: Sequence[str] | None = None) -> int:
+    parser = argparse.ArgumentParser(description="Close older same-repository Windows version-sync PRs.")
+    parser.add_argument(
+        "--repository",
+        default=os.environ.get("GITHUB_REPOSITORY"),
+        help="GitHub repository in owner/name form (defaults to GITHUB_REPOSITORY).",
+    )
+    parser.add_argument("--current-pr", type=int, required=True)
+    parser.add_argument("--current-version", type=parse_version, required=True)
+    args = parser.parse_args(argv)
+    if not args.repository:
+        parser.error("--repository or GITHUB_REPOSITORY is required")
+    if args.current_pr <= 0:
+        parser.error("--current-pr must be positive")
+
+    retire_superseded_prs(
+        repository=args.repository,
+        current_pr=args.current_pr,
+        current_version=args.current_version,
+    )
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/.github/scripts/test_retire_superseded_windows_sync_prs.py b/.github/scripts/test_retire_superseded_windows_sync_prs.py
new file mode 100644
index 00000000000..7ee45b79390
--- /dev/null
+++ b/.github/scripts/test_retire_superseded_windows_sync_prs.py
@@ -0,0 +1,164 @@
+#!/usr/bin/env python3
+"""Tests for retiring superseded Windows release sync PRs."""
+
+from __future__ import annotations
+
+import importlib.util
+import io
+import json
+import subprocess
+import sys
+import unittest
+from pathlib import Path
+
+_SPEC = importlib.util.spec_from_file_location(
+    "retire_superseded_windows_sync_prs",
+    Path(__file__).with_name("retire_superseded_windows_sync_prs.py"),
+)
+sync_cleanup = importlib.util.module_from_spec(_SPEC)
+sys.modules[_SPEC.name] = sync_cleanup
+_SPEC.loader.exec_module(sync_cleanup)
+
+
+def pull_request(
+    number: int,
+    branch: str,
+    *,
+    base: str = "main",
+    cross_repository: bool = False,
+) -> dict[str, object]:
+    return {
+        "number": number,
+        "headRefName": branch,
+        "baseRefName": base,
+        "isCrossRepository": cross_repository,
+    }
+
+
+class FakeRunner:
+    def __init__(
+        self,
+        payload: object,
+        *,
+        list_returncode: int = 0,
+        close_failures: set[int] | None = None,
+    ) -> None:
+        self.payload = payload
+        self.list_returncode = list_returncode
+        self.close_failures = close_failures or set()
+        self.calls: list[list[str]] = []
+
+    def __call__(self, args: list[str], **_: object) -> subprocess.CompletedProcess[str]:
+        self.calls.append(args)
+        if args[:3] == ["gh", "pr", "list"]:
+            return subprocess.CompletedProcess(
+                args,
+                self.list_returncode,
+                stdout=json.dumps(self.payload),
+                stderr="list failed" if self.list_returncode else "",
+            )
+        number = int(args[3])
+        return subprocess.CompletedProcess(
+            args,
+            1 if number in self.close_failures else 0,
+            stdout="",
+            stderr="close failed" if number in self.close_failures else "",
+        )
+
+    @property
+    def closed_numbers(self) -> list[int]:
+        return [int(args[3]) for args in self.calls if args[:3] == ["gh", "pr", "close"]]
+
+
+class RetireSupersededWindowsSyncPRsTests(unittest.TestCase):
+    def test_closes_only_older_same_repository_main_sync_prs(self) -> None:
+        runner = FakeRunner(
+            [
+                pull_request(10723, "release/windows-v1.0.26"),
+                pull_request(10419, "release/windows-v1.0.3"),
+                pull_request(10718, "release/windows-v1.0.25"),
+                pull_request(10730, "release/windows-v1.0.27"),
+                pull_request(10684, "release/windows-v1.0.22", cross_repository=True),
+                pull_request(10653, "release/windows-v1.0.21", base="development"),
+                pull_request(10000, "release/windows-maintenance"),
+            ]
+        )
+        stdout = io.StringIO()
+
+        closed = sync_cleanup.retire_superseded_prs(
+            repository="BasedHardware/Omi",
+            current_pr=10723,
+            current_version=(1, 0, 26),
+            runner=runner,
+            stdout=stdout,
+            stderr=io.StringIO(),
+        )
+
+        self.assertEqual(closed, 2)
+        self.assertEqual(runner.closed_numbers, [10419, 10718])
+        close_calls = [args for args in runner.calls if args[:3] == ["gh", "pr", "close"]]
+        self.assertTrue(all("--delete-branch" not in args for args in close_calls))
+        self.assertTrue(all("#10723" in args[args.index("--comment") + 1] for args in close_calls))
+        self.assertIn("Retired 2 superseded", stdout.getvalue())
+
+    def test_skips_cleanup_unless_the_current_pr_is_confirmed(self) -> None:
+        runner = FakeRunner([pull_request(10419, "release/windows-v1.0.3")])
+        stderr = io.StringIO()
+
+        closed = sync_cleanup.retire_superseded_prs(
+            repository="BasedHardware/Omi",
+            current_pr=10723,
+            current_version=(1, 0, 26),
+            runner=runner,
+            stdout=io.StringIO(),
+            stderr=stderr,
+        )
+
+        self.assertEqual(closed, 0)
+        self.assertEqual(runner.closed_numbers, [])
+        self.assertIn("current Windows sync PR #10723 was not confirmed", stderr.getvalue())
+
+    def test_close_failure_is_nonfatal_and_does_not_stop_cleanup(self) -> None:
+        runner = FakeRunner(
+            [
+                pull_request(10723, "release/windows-v1.0.26"),
+                pull_request(10419, "release/windows-v1.0.3"),
+                pull_request(10718, "release/windows-v1.0.25"),
+            ],
+            close_failures={10419},
+        )
+        stderr = io.StringIO()
+
+        closed = sync_cleanup.retire_superseded_prs(
+            repository="BasedHardware/Omi",
+            current_pr=10723,
+            current_version=(1, 0, 26),
+            runner=runner,
+            stdout=io.StringIO(),
+            stderr=stderr,
+        )
+
+        self.assertEqual(closed, 1)
+        self.assertEqual(runner.closed_numbers, [10419, 10718])
+        self.assertIn("could not close superseded Windows sync PR #10419", stderr.getvalue())
+
+    def test_list_failure_is_nonfatal(self) -> None:
+        runner = FakeRunner([], list_returncode=1)
+        stderr = io.StringIO()
+
+        closed = sync_cleanup.retire_superseded_prs(
+            repository="BasedHardware/Omi",
+            current_pr=10723,
+            current_version=(1, 0, 26),
+            runner=runner,
+            stdout=io.StringIO(),
+            stderr=stderr,
+        )
+
+        self.assertEqual(closed, 0)
+        self.assertEqual(runner.closed_numbers, [])
+        self.assertIn("could not list Windows sync PRs", stderr.getvalue())
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/.github/workflows/desktop_windows_release.yml b/.github/workflows/desktop_windows_release.yml
index aabdbbeaf57..0d02e4dc4ad 100644
--- a/.github/workflows/desktop_windows_release.yml
+++ b/.github/workflows/desktop_windows_release.yml
@@ -178,6 +178,15 @@ jobs:
           fi
 
           if [ -n "$PR_NUMBER" ]; then
+            # A newer tag makes every older version-stamp PR obsolete. Confirm
+            # the replacement PR before closing only older same-repo sync PRs;
+            # cleanup never deletes tags, releases, or branches and is non-fatal.
+            python3 .github/scripts/retire_superseded_windows_sync_prs.py \
+              --repository "$GITHUB_REPOSITORY" \
+              --current-pr "$PR_NUMBER" \
+              --current-version "$VERSION" || \
+              echo "Could not retire superseded Windows sync PRs (non-fatal)."
+
             gh pr merge "$PR_NUMBER" --merge --admin || \
             gh pr merge "$PR_NUMBER" --merge --auto || \
             gh pr merge "$PR_NUMBER" --merge || \